It is a lesson they should have learned in 1998.
 Republicans expected to make large gains in Congress that year but ended up losing five House seats and standing pat in the Senate. The problem was not so much that Republicans “overreached” in pursuing the impeachment of President Clinton, as the conventional wisdom has it. The Republicans that year did not really run on a promise to remove Clinton from office — or on any other agenda. Their strategy was to assume that the scandal would redound to their benefit, and that they merely had to sit back and let victory rain o’er them. It didn’t.

The current lot should not make the same mistake. Democratic scandal does not take the place of a Republican agenda. It does not reform the tax code or reduce the debt or ease regulatory burdens on small business. It cannot substitute for a strategy to replace Obamacare. By all means, Republicans should run against the president and his party — against their refusal to take the entitlement crisis seriously, against the implementation of their “train wreck” health-care law, and even against the unusually politicized executive-branch culture that contributed to the post-Benghazi cover-up. They should at the same time understand that a purely negative message, however justified, will not produce the governing majority Republicans should be aiming for in the next two elections.

Even worse than relying on scandal would be advertising the fact. Republicans should not indulge in public speculation about the electoral repercussions of these scandals for 2014 (much less 2016!). Doing so plays into the Democrats’ hands by making legitimate inquiries seem like opportunistic partisan exercises, and is thus likely to be a self-canceling prophecy.